there is a small peak in the radiohalos frequency data in Fig. 6 around 80-120 Ma, but that is dominated by one granite. However, more sampling of Phanerozoic granites, including those claimed to be 0-200 Ma in age, would potentially provide infill data in Fig. 6. Nevertheless, the most recent granites might not have many radiohalos in them anyway, as evident in Table 1 and Fig. 6, due to 100 million years’ worth of accelerated 238U (at today’s measured rate) being needed to form good visible radiohalos. Also, the grossly accelerated 238U decay rate during the Flood may have started to rapidly decelerate as the Flood ended and tectonic activity also started to decelerate. C. Hydrothermal fluid activity during the Flood In most instances, the granites and regional metamorphic rocks listed in Tables 1 and 2 have Po radiohalos in them, often more in number than the 238U radiohalos they accompany frequently in the same biotite grains (91 out of 124 granites or ~73%, and 20 out of 23 metamorphic rocks or ~87%) (Fig 4). According to the hydrothermal fluid transport model for the formation of Po radiohalos (Snelling and Armitage 2003; Snelling 2005a) the greater the number of Po radiohalos in a granite or regional metamorphic rock is due to greater water flow, that is, hydrothermal fluid activity. This was predicted and then verified in case studies by Snelling (2008b, c, d, 2014, 2018) and Snelling and Gates (2009). Furthermore, many of the granites with the highest radiohalos frequency (Tables 1 and 2, Figs. 5 and 6) are granites that host or are genetically associated with hydrothermal metallic ore deposits, such as the Land’s End and Bodmin Moor Granites of England (Moscati and Neymark 2020), and the Hillgrove and Mole Granites of the New England region of eastern Australia (Ashley et al. 1994: Ashley and Craw 2004; Audétat et al. 2000a, b; Comsti and Taylor 1984; Kleeman et al. 1997; Schaltegger et al. 2000). Indeed, Snelling (2018) demonstrated that the Po radiohalos in the latter two granites correlated with the hydrothermal ore veins and could thus be used as an exploration pathfinder for other hydrothermal ore deposits associated with unexplored granites. The hydrothermal fluid activity during the Flood is thus easily recognized in Figs. 5 and 6, as just discussed. However, what of the smaller peaks in radiohalos frequency in the Precambrian (or preFlood) granites and regional metamorphic rocks in Fig. 5? Since any previously-generated radiohalos in these rocks would have been annealed as these rocks were subjected to the heat generated by the accelerated decay of any 238U still in them during the Flood, the Po radiohalos now observed in these rocks must be due to hydrothermal activity during the Flood. Yet, according to the hydrothermal fluid transport model for Po radiohalos formation (Snelling and Armitage 2003; Snelling 2005a, Snelling 2008a), the peak window for hydrothermal fluid activity and thus the formation of Po radiohalos is after the heat involved in the formation of the host rocks is waning and those host rocks have cooled below 150°C. However, by the time of the onset of the Flood those Precambrian granites and regional metamorphic rocks had already formed and cooled. Thus, the Po radiohalos now observed in them had to be generated by the heating during the Flood of whatever ground water had penetrated into them in the pre-Flood world, and/or by whatever hydrothermal fluids were injected into them during the Flood. By either process those pre-Flood rocks would have been less proficient at generating copious quantities of Po radiohalos, certainly not at the levels of “freshly-made” Flood granites, especially those that expelled huge amounts of hydrothermal fluids from the granitic magmatic fluids to also produce associated metallic ore veins. So why would the Precambrian regional metamorphic rocks in many instances be better at generating new Po radiohalos during the Flood compared to the Precambrian granites (Fig. 5)? The best example is the Vishnu Schist in the Grand Canyon that contains many more radiohalos per slide than either the Ruby Granodiorite or Zoroaster Granite that were previously intruded in it (Ilg et al. 1996; Karlstrom et al. 2003) (Tables 1 and 2). The answer would be that the Vishnu Schist consists of many more biotite grains than in either of those two granites, so the Vishnu Schist has many more perspective 238U-bearing zircon inclusions within those many more sheeted biotite grains which are conducive to fluid flow between the sheets to transport Po and thus generate more Po radiohalos. D. The Flood/post-Flood boundary Given the process of radiohalos formation in granites, whereby at least 100 million years’ worth of accelerated 238U decay (at today’s measured rate) is needed to form good visible radiohalos, it is difficult to draw any conclusions from the radiohalos frequency data plotted in Fig. 6 regarding the location of the Flood/post-Flood boundary in the rock record. That is because there is insufficient “geologic” time left in the Cenozoic (only 66 million years) for the accumulation of enough α-particles from 238U and Po decay to have generated many good visible radiohalos. However, there was still one sampled Cenozoic granite that contained radiohalos, especially Po radiohalos, and is conventionally dated at Oligocene (c. 33 Ma), whereas the other Cenozoic granites contained no radiohalos (Table 1 and Fig. 6). Two main scenarios have been suggested for the boundary in the rock record that represents the Flood/post-Flood boundary, and each scenario has an accompanying implication for when the accelerated radioactive decay decelerated. The first scenario is that the Flood/ post-Flood boundary corresponds roughly with the Cenozoic or Paleogene/Cretaceous boundary at 66 Ma in the rock record (Austin et al 1994; Whitmore and Garner 2008). This scenario involves the continuation of accelerated radioactive decay during the ensuing Cenozoic, though perhaps it began to progressively decelerate. The second scenario places the Flood/post-Flood boundary at or close below the Quaternary/Neogene boundary or alternatively the Pliocene/Miocene boundary in the rock record at approximately 3 Ma or 5-7 Ma (Clarey 2020). Accelerated radioactive decay would likewise have continued through the Cenozoic before decelerating at the end of the Cenozoic. The second scenario is attractive to many as it avoids the harmful bi-products of accelerated radioactive decay (heat and radiation) in the post-Flood era, especially for humans, animals, and plants. Since both scenarios involve accelerated radioactive decay continuing through the Cenozoic, the radiohalos frequency data plotted in Fig. 6 do not allow any definitive demarcation of the Flood/post-Flood boundary in the rock record. All the data show is they are consistent with the drop-off in radiohalos frequency at and below approximately 80 Ma due to the 100 million years’ worth of accelerated 238U decay SNELLING Radiohalos through earth history 2023 ICC 556
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